Add a hint about using --no-isolate for GDB.

Change-Id: Ib9df5ed986a1c4082c9c7cd793a4d670be21ca66
diff --git a/ b/
index 72b7124..37d3f62 100644
--- a/
+++ b/
@@ -257,6 +257,17 @@
 The coverage report is now available at `covreport/index.html`.
+Attaching GDB to the tests
+Bionic's test runner will run each test in its own process by default to prevent
+tests failures from impacting other tests. This also has the added benefit of
+running them in parallel, so they are much faster.
+However, this also makes it difficult to run the tests under GDB. To prevent
+each test from being forked, run the tests with the flag `--no-isolate`.
 LP32 ABI bugs